1. Field
Embodiments of the invention relate to the field of networking; and more specifically, embodiments of the invention relate to synchronizing clocks located on a network element.
2. Background
A network element is a piece of networking equipment, including hardware and software that communicatively interconnects other equipment on the network (e.g., other network elements, computer end stations, etc.). Network elements may need to be synchronized. Typically network elements include multiple line cards which may be independently timed. In addition, some network elements allow multiple operators (e.g., service providers) to share one or more line cards and may each maintain their own timing synchronization hierarchy. Existing synchronization methods include network based and channel based methods. Network based methods rely on packet based protocols, such as the Network Time Protocol (NTP) described in Internet Engineering Task Force (IETF) draft “Network Time Protocol Version 4 Protocol And Algorithms Specification”, Jul. 14, 2008, to distribute timing between the network elements. Channel based methods use a physical circuit or a radio channel to transmit timing information (for example, the Global Positioning System (GPS)). The network based methods offer greater flexibility and scalability, while the circuit based methods offer higher precision.
One prior art technique of network based clock synchronizing is the Institute of Electrical and Electronics Engineers (IEEE) 1588-2008 standard, “IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems”, Mar. 27, 2008 (hereinafter “the IEEE 1588 standard”). The IEEE 1588 standard is a protocol designed to synchronize real-time clocks in nodes of a distributed system that communicate using a multicast capable network, such as Ethernet. In addition, the IEEE 1588 standard provides for a protocol known as the precision time protocol (PTP).